How Long Until I Can Play?
This is an impossible to forecast, unfortunately. But the reason people ask it is important. To set expectations as accurately as possible prior to making any significant investment of time, money, and energy is prudent and judicious.
To that end, I would strongly urge that you document the first six weeks from starting guitar lessons. Record a short video of your playing before, during, and after that six weeks period. Upon reviewing that documentation at end of six weeks, as well as having gained an insight from the lessons as to what will be required of you in future, you’ll be in an excellent position to discern whether the investment is worth it.
How Should I Practice?
This is an excellent question, and I think an excellent answer would constitute a clear and simple one:
Practice a minimum of seven minutes per practice session, and use a timer. You’re allowed to miss a day if you must, but don’t miss two days in a row. If you stick to that rule, then you can’t miss three, or four, twenty, etc. So under that structure, at the very worst you’ll be playing half the days of the years, which isn’t bad.